Recent population changes in the United States indicate increases in the number of married women expecting to have only one child. This possible increase points to a need for more information about only children. The major objective of the present study is to investigate some of the effects of growing up without siblings. The research aims to test hypotheses about: (1) differences in self-esteem, locus of control and leadership skills between only and nononly children and (2) differences in autonomy, cooperativeness, and leadership skills between only and nononly children. All hypotheses will be tested while controlling for differences in socioeconomic status, family size, sex, age spacing between sibling and other factors affecting the dependent variables. Two sources of data will be used. The first is a survey of students at the University of Texas, Austin, and the second is a laboratory experiment to be set up on the basis of the results of the survey. The techniques of analysis will be combination of analysis of covariance, partial correlation, and chi-square.